Inflatable liferafts enclosed in the self-opening containers are well known and are used as mandatory life-saving equipment throughout the world on almost any commercial ship and vessel of a given size.
In this context the liferaft in its container can be considered to be permanently secured to the ship and are normally only dismounted when the liferaft is to be serviced at a land-based service-station, e.g. once yearly, or when other types of maintenance takes place on the ship.
Indeed, when the liferaft is deployed in an emergency case the container is liberated corresponding to its mounting means and, typically, dropped into the water where the container will open and the liferaft inflate. The typical size for such a permanently mounted liferaft may be for 4 to 150 persons.
As mentioned above the liferafts are according to SOLAS Rules (Convention for the Safety of Life at Sea) to be inspected and serviced periodically. The reason for this is to obtain the highest degree of safety and for enabling a reliable checking as well as maintenance of the liferafts.
In the known service-checks the liferafts are dismounted from the ship or vessel, for instance when being in a harbour, and transported to an authorised service-station. At the service-station the liferafts are unpacked, inflated and then inspected. The inspection reveals any damage on the liferafts either on the material of the liferaft or for instance corrosion on metal parts. Furthermore, the means for inflating the liferaft is being inspected.
In addition to the physical inspection of the liferaft, the service-check may also contain replacement of elements, which are enclosed in the liferafts, and which have limited durability such as for instance batteries, medicine, distress signals or emergency rations.
After the inspection (and possible repair) and the replacement of the above mentioned elements the liferaft is repacked and replaced in the container and finally returned to the ship or vessel.
The above mentioned service-checks are time consuming. Furthermore, due to the fact that the service-check takes long time to execute, the ship or vessel, whereupon the liferafts are situated, has to stay in the harbour, which may be expensive for the shipowner. There is thus a need for providing a liferaft having less time consuming service-checks.
The liferafts are stored on the deck of a ship or vessel, which may expose the liferafts for different environmental changes such as wind, sun, salt, water and/or moisture. The outer container, which houses the liferaft, is capable of protecting the liferaft against the mechanical actions, however, it is not suitable for protecting the liferaft against for instance moisture. The reasons for this is that in the prior art it has not yet been possible to provide a secure sealing of the container.
When the liferaft is exposed to moisture it may have the result that the material of the liferaft is starting to be weakened, which may reduce the life of the liferaft.
Furthermore, moisture, especially salt containing moisture, has corrosion effect on the different metal parts or attachments on the liferafts.
For protecting the inflatable liferaft it is known to place the liferaft in a bag, and provide the bag with a vacuum, as for instance described in GB 2 296 482.
However, it is known in the prior art that constant mechanically actions, such as for instance sharp bends of the material of the liferaft, may result in a weakening of the material. As the bag is exposed to the vacuum the liferaft is pressed further together in the bag which additionally provides more sharp bends of the material and thereby additional weakening of the material.
Furthermore, the vacuum bag has the disadvantage that if the bag breaks, air and thereby moisture will be sucked into the bag, which also may provide weakening to the material of the liferaft.
There is thus a need for providing a liferaft, which is not exposed for a constant pressure, i.e. vacuum as well as for providing a liferaft, which is protected against the outer environment, and a liferaft which condition may be measured without unpacking said liferaft.